Tube cracking machine



Nov. l2, 1946. c. ElsLER- 2,410,931

TUBE GRACKING rvfAcHINE` Filed March 30, 1944 2 Sheets-Sheet 1 Mzwwuuvnum ,i la. I .%H.,. ...n.m.,#.uwwm P M v i. A .1. l m l lll nw l l! l/ IIN e ,Maw/W4 .w 3 5 M f M Mw 5 mw x .d/ P, 4 f n a., M O l 1 3 9 .x 4 O v I e @4 4 J l o o s HIM a I w k 2 f 4 d Mo IelI.. ,IIIIIII I I f I 3 1 Jv o 3 a HI 4 m, 4 l lvl FGW I |.wl I Il q/v 4 ...M b I I I I IIII .e Inl.. l Av. .hn lr E f, If. Il: /IrIxHNlV Nov. 12, 1946. c. ElsLER 2,410,931

TUBE CRACKING MACHINE Filed March so, 1944 2 sheets-sheet 2 IN VEN TDR Patented Nov. 12,1 1946 UNITED f STATES PATENT OFFICE c 2,410,931". y TUBE CRACKVINGMACHINE Charles Eisler, South OrangeLNJ. Y Application March 30, 1944, Serial No. 528,812

This invention relates to a machine for reducing the length of glass tubes and is particu' larly designed t crack olf the end or ends of glass tubes of comparatively large diameters and with thin walls such as are used in lighting, the inside of the tubes having a fluorescent coating.

The present machine employs a hot Wire cracking method in conjunction with specially designed mechanical means and a specially designed cracking knife. The machine as disclosed in this application has been found to cut off or crack the end of a thin-Walled glass tube leaving a smooth even edge with no jagged parts to interfere with the accurate mounting of a tube in a xture. By this means a tube of the proper length can be accurately produced and this `without any damage to any fluorescent lining that the tube might have.

The invention is also designed to provide a machine that can be conveniently adjusted to provide for various lengths of tubes and containing details of construction to be more fully described hereinafter and also embodied in the claims.

The invention is illustrated in the accompanying drawings, in which Figure 1 is a plan view of a machine for simultaneously processing two tubes. Figure 2 is a cross-section of the upper part of the machine showing the appliances used in the cracking-off operation, and Figure 3`is an end elevation of the machine and also illustrating the mechanism for rotating the tubes.

The machine is provided with a, base frame 5 provided with a shelf 6 and the top I which supports the side frames 8 and 9, to the top of which are secured the multiple bearing members and |2 respectively by means of the bolts I0.

The spindles I6, |I and I8 are journalled in the bearings I3, I4 and I5, respectively. The rollers I9, 2|) and 2| are secured on the spindles I6, Il and I8 respectively and form a cradle for the glass tubes 22 and 23, the spindles being spaced close enough together to provide the proper support.

The motor 24, by means of the belt 25, the speed-reduction unit 26 and the transmission 21 drives the shaft 28 on which is mounted the pulley 29, which, by belt 30, drives the pulleys 3|, 32 and 33, which are secured on the spindles I6, Il and I8. The adjustable idler 34 is interposed to insure proper traction of the belt 30. The rollers I9, 2|) and 2| are thus rotated in unison and impart rotation to the tube or tubes supported on them.

On the shafts 35 and 36 fixed on the side frames 8 and 9 are slidably mounted the transverse 4 claims. (o1. r9- 50) plateslor supports V3l. and 38 which can be fixed at any distance to control the required length of the glass tubes. .The plates are-secured in place by the set-screws 39. Each transverse plate carries the vertical electrodes in pairs, 40 and 4I,

and l2 and 43, screwed into the insulating bush-4 ings fili, the electrode pairs being connected in series by the heating wires 45 and the terminal 45, current being supplied by the secondary coil 4l of the transformer 28 through the exible conduits 49 and 50.

The heating wires 45 are bent in a semi-circle to form a loop so as to partly encompass the revolving glass tube with a slight clearance in order to avoid direct heating contact with the glass, as contact would cause sudden over-heating of the glass which would result in premature cracking and breaking of the tubes. The tubes are therefore locally heated, gradually and uniformly at the desired locations, the actual cracking off being then accomplished by the keen edge of the Carborundum knives 5|. The Carborundum or similar knives 5| are secured to the arms 54 by the washer plates 52 and bolts 53. In the form shown the arms 54 are secured on the shafts 55. The knives 5| are in exact alignment with the heating wires 45 so that when the shafts 55 are turned by levers 56 actuated by foot treadle 5l, the knives will tap the glass tube exactly at the heated section. This causes the tube to crack neatly at the heated section, the cracked off ends dropping onto the table l. The construction shown includesthe foot treadle 51 which is connected by links or Wires with the lever 56 of the shafts 55. The arms 54 with the knives are subsequently returned to non-operative position by the counterweights 58.

In the machine shown for two tubes, it is assumed that both tubes 22 and 23 are cracked oil at the same time since it requires little time to heat the tubes to the required temperature for cracking off, and the capacity of the machine is more than if tubes were alternated in the machine.

I claim:

l. A tube cracking machine comprising a frame member, rollers rotatably supported in said frame in parallel, spaced relation, said rollers being adapted to rotatably, horizontally support the tube to be cracked, a heat-imparting ,wire member of generally semi-circular outline positioned in said frame in alignment with and spaced adjacent the position of said tube to encompass the lower portion of the tube, an arm pivotally mounted in said frame in alignment with said Wire, said arm having a free end remote from its point of pivot, a. knife on the free end of the arm, and means to pivotally move the arm, said arm being of such proportions and being so positioned in said machine that it may be pivoted to bring the knife into contact with the tube at a point in alignment with and above the position of the Wire member.

2. A tube cracking machine comprising a frame member, rollers rotatably supported in said frame in parallel, spaced relation, said rollers being adapted to rotatably, horizontally support the tube to be cracked, a heat imparting Wire member of generally semi-circular outline positioned in said frame in alignment with and spaced adjacent the position of said tube to encompass the lower portion of said tube, an arm mounted in said frame in alignment with said Wire, a knife on said arm, and means to move the arm to bring the knife into contact with the tube at a point in alignment with the position of the Wire member.

3. A tube cracking machine comprising a, frame member, means in said frame to rotatably, horizontally support the tube to be cracked, a heat imparting Wire member positioned in said frame in alignment with and spaced adjacent the position of said tube to encompass a portion of the tube, an arm mounted in said frame in alignment with said wire, a knife on said arm, and means to move the arm to bring the knife into contact with the tube at a point in alignment With the position of the wire member.

4'. A tube cracking machine comprising a, frame member, means in said frame to rotatably, hori- Zontally support the tube to be cracked, a heat imparting Wire member positioned in said frame in alignment with and spaced adjacent the position of said tube therein to encompass the lower portion of the tube, an arm pivotally mounted in said frame in alignment with said wire, a knife xed to said arm, and means to move the arm to bring the knife into contact with the tube at a point in alignment with the position of the Wire member.

CHARLES EISLER. 

